Michelson interferometers are commonly used as optical filters or “nullers,” which destructively interfere a particular wavelength of radiation and thereby strongly attenuate its amplitude. This is accomplished by translating a moveable mirror in one of the two legs of the Michelson interferometer to introduce a optical path length difference between the two beams. The resulting null, however, covers a very narrow range of wavelengths, centered around a wavelength where the path difference is an odd integer multiple of 0.5 wavelengths.
Accordingly, there is a need to provide an interferometer which can null a broader range of wavelengths than is possible with a conventional Michelson interferometer. The present invention satisfies this needs and provides other advantages as well.